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Studies were undertaken to evaluate the effects of caloric restriction on voluntary exercise in a rat model of pancreatic cancer. Suckling male Lewis rats were initiated with 3 doses (30 mg/kg body weight) of the pancreatic carcinogen azaserine. At 28 days of age they were weaned to one of four experimental protocols; namely, sedentary/ad libitum fed, voluntary exercise/ad libitum fed, sedentary/food restricted, and voluntary exercise/food restricted. Voluntary exercise was provided by free access to running wheels fitted with odometers. Food restriction was intended to be mild, at less than 10% reduction of ad libitum intake. Putative pre-neoplastic pancreatic foci were identified microscopically at 4 months post-azaserine treatment. As previously shown, food restriction led to increased wheel activity, but the increased activity could not be maintained beyond the first half of the post-initiation treatment phase. Additionally, the extensive wheel running occurred only when available food was restricted by greater than 10%. Exercise per se had a lesser effect compared to food restriction on pancreatic tumorigenesis.

Foods containing soybean products have been shown to modify the biochemical and physiological status of the pancreas of several species of experimental animals. Recently, these products have been implicated as a factor in the causation of pancreatic neoplasms. Extensive experimental studies into the possible mechanisms need to be undertaken. Experimental details of a rat/azaserine model for the study of pancreatic carcinogenesis are reviewed. Emphasis is given to the quantitative components of this model and the adaptation of this model to the two-stage (initiation-promotion) concept of carcinogenesis. Particular attention is devoted to considerations of the experimental diets. Application of these concepts to the study of the postinitiational effects of raw and heated soybean protein isolate with and without the addition of high levels of unsaturated fat were undertaken. The results indicate that raw soybean isolate enhanced the growth of azaserine-induced pancreatic foci; whereas, a high level of unsaturated fat had a minimal effect. The effects of the soybean isolate were abolished by heat treatments, but the effects of the unsaturated fat would not be expected to be abolished by similar treatment with heat.